Technical Field
The present invention relates to semiconductor technology field, and particularly to a method of aligning a quadrate wafer during a first photolithography process.
Description of the Related Art
It is common that only a quadrate or rectangular die can be produced due to limitation from cutting a wafer during manufacturing dies from the wafer, which renders waste during cutting a circular wafer in virtue of cutting lots of incompleted dies at periphery of the wafer. By comparison, for a quadrate or rectangular wafer, no incompleted die is formed during cutting the quadrate wafer as the edges of the quadrate wafer are parallel to a cutting direction and are different from the arc edge of the circular wafer.
During manufacturing dies from a wafer, a plurality of processes are needed, including mesa etching, electrode defining, passivation protecting, and thus a series of mask patterns for various processes are needed. As for a circular wafer, it can be exposed under a first mask directly since it is not needed to be aligned to the mask during a first exposure process. A second mask may be aligned to the wafer according to a formed aligning marker formed at a corresponding position of the wafer through the first mask, and so on. However, it is impossible to ensure integrity of dies formed at edges of a quadrate wafer by implementing the above photolithography mask alignment way. As shown in FIG. 1, reference number 21 indicates four sides of a quadrate wafer, and reference 22 indicates dies formed from the quadrate wafer through an existing photolithography process. As shown in FIG. 1, the dies at edges of the quadrate wafer are not intact due to lack of photolithography alignment, which renders waste product.